The present invention relates to a light metering or photometric device used for metering a scene brightness for determining a proper exposure.
In recent photometric or light metering devices for metering the brightness of a scene to be photographed, an image plane is divided into a plurality of divisional areas, and the respective divisional areas are independently measured in brightness. Usually, such a light metering device generates outputs representing the brightness of the scene correspondingly to the divisional areas of the image plane. The outputs are separately weighted and are added together to provide integrated or collective brightness information based on which a proper exposure for the scene is determined.
For instance, in a center weighted metering system for emphasizing a lower area (which is hereinafter referred to as a lower area emphasizing center weighted metering system in this specification), in which the brightness of lower left and lower right areas surrounding the subject person is weighted secondly to the brightness of a principal or intended part of a subject, upper and lower light metering areas are formed in addition to and on both sides of a circular outlined light metering area defined at the center of an image plane, and these three light metering areas are differently weighted in photometric sensitivity in such a way that the center light metering area has the greatest photometric sensitivity and the upper light metering area has the smallest photometric sensitivity, among the three, respectively. When taking a picture of the general scene including a person or persons as a principal subject with the use of cameras equipped with such a lower area emphasizing center weighted metering device, the brightness of the face of the subject person is taken as of major factor of exposure determination, along with taking the brightness of areas surrounding the subject person in the lower area into account. In addition, the brightness of the upper area, which is generally affected by sun light, is treated lightly. Therefore, in major cases, a proper exposure can be given for the principal subject.
The above mentioned lower area emphasizing center weighted metering device, by metering the lower area independently from the center area for weighting differently the center, upper and lower metering areas is, however, accompanied with a problem that the brightness of clothes of a person as a principal subject will greatly affect the resultant brightness information obtained by the lower part emphasizing center weighted metering device. when taking a group picture, since the lower metering area which is weighted to some extent meters the light from the clothes of the persons, the faces of the persons will be different in density on a print even when they are uniformely lit.